Resonance devices using MEMS (Micro Electro Mechanical Systems) techniques have been used as a timing device, for example. This type of resonance device is mounted on a printed circuit board that is incorporated in an electronic apparatus such as a smart phone or the like. The resonance device is provided with a lower side substrate, an upper side substrate forming a cavity between the lower side substrate and the upper side substrate, and a resonator disposed in the cavity between the lower side substrate and the upper side substrate.
For example, Patent Document 1 (identified below) discloses a resonator provided with a plurality of vibration arms. In this resonator, fixed ends of the vibration arms are connected to a front end of a base section, and the base section is connected to a supporting unit at a rear end thereof which is on the opposite side to the front end. The supporting unit is, for example, connected to a base unit sandwiched between a lower side substrate and an upper side substrate. In an example of FIG. 1 of Patent Document 1, by electric fields applied to the vibration arms being set in reverse directions to each other, vibrations having reverse phases to each other are generated between an inner side vibration arm and two outer side vibration arms.
Patent Document 1: Japanese Patent No. 5071058.
Patent Document 2: Japanese Unexamined Patent Application Publication No. 56-085921.
As shown in FIG. 1(c) of Patent Document 1, during the vibrations with reverse phases, torsional moment is generated in each of the vibration arms around a center axis extending in a direction parallel to a Y axis. Due to this torsional moment, in the base section of the resonator, between the center axes of the adjacent vibration arms vibrating with reverse phases, bending vibrations are generated around a rotational axis defined in parallel to the center axis. The vibrations are transmitted from the base section to the base unit through the supporting unit. The vibrations are attenuated to some extent in the base unit because the base unit is held between the lower side substrate and the upper side substrate.